Character Physics is a physics engine built completely in python. In a nutshell it allows you to treat armatures like physics objects. Just like you can set up lamps to get realistic lighting and shadows without having to fill in all the details by hand, you can use character physics to get the subtle nuance of real life motion with very little effort.

Character Physics is a new animation paradigm but it's easy to get used to. It's best to start with a simple rig with all child bones connected to their parents. Once you have a simple rig you can duplicate it then under "Setup" select the duplicate as a "Pose Target." If you already detailed character rigs set up it's easy to create a simple Character Physics rig with constraints to control your existing rigs.

Once you have a pose target that matches your original armature in the number and configuration of bones you're ready to go. Now when the animation runs, or if you set "Live" to true under "Record Playback," your armature will come to life with gravity, velocity, collisions, friction and much more. Once you've been through setup, you can begin posing your pose target, or use any of Blender's animation tools with the pose target, then you can see how the physics armature attempts to match the pose wile contending with gravity, velocity, collisions etc.

For fine-tuned control of your rig you can add influence targets that will behave like linear springs, angular springs, or add constant motion with whatever force and in whatever direction you like. You can use this to get all sorts of effects. For example you can create a wrecking ball swinging on a chain.

If you want your rig to interact with mesh objects simply set your mesh to "collider." Now your armature will collide with the mesh. You can set the friction of the whole mesh or use the friction vertex group (automatically created for you) to control the friction. With each bone you can set the collision size so your character mesh collides correctly with external objects.

Under the physics settings you can tweak the behavior or your characters in endless ways. For example, let's say you want to animate the wings of a dragon. Where the wing connects to the body you probably want a strong angular force. Towards the ends of the wings you probably want the wings to flex more so you can set the rotation force lower to make it seem like the wings are moving in the wind.

Keep in mind you can build rigs like you might build a machine. Feel free to build stabilizers around a character to prevent your characters from falling over. You can also use influence targets for similar effects.

Motion capture cleanup tools allow you to easily make changes to motion capture data. You can do things like add collisions to existing data, fix outliers, change the stance of your character while keeping the general data intact. It's all done by mixing physics effects with mocap data used as a scalable influence on the physics.